A thermoplastic elastomer (TPE) includes a soft segment having elasticity and a hard segment to prevent thermoplastic deformation in molecules. TPEs can be a subject of a shaping process during processing like a thermoplastic plastic, and have elasticity of thermosetting rubber at room temperature. By properly designing soft and hard segments, various physical properties may be obtained.
TPEs have been used in many different fields such as shoes, sticking agents, adhesives, automobiles, industrial products, architecture•civil engineering•ocean, wires•cables, electronics•electricals, sport equipment, packing materials, and medicinal products, etc. Also, TPEs have been massively used as a commercialized material of a plastic improver or polymer alloy. TPEs are used for electronic•electrical components or cameras through the alloy. Besides, TPEs have received much attention, because TPEs confer functions such as conductivity, photosensitivity, and selective isolation, thereby being used for high functional use in the electronic optical field, medicinal field, and printing fields. Particularly, the application to medicinal products as a high purity rubber material without the use of vulcanizing agents has been mostly noted and developed.
During the development and study of TPE products, through combination of types, molecular weights, and arrangement of the soft and hard segments, high performance and high functionality have been studied. Also, TPEs have been gradually varied and diversified. Further, needs for TPEs has been increased every year due to rising concerns about environment and continuous development of uses, and therefore the markets are actively expanded.
Depending on used materials, TPEs have been divided into olefin-based (thermoplastic olefinic elastomer, TPO), styrene-based (thermoplastic styrenic block copolymer, SBC), urethane-based (thermoplastic polyurethane, TPU), amide-based (thermoplastic polyamide, TPAE), and polyester-based (thermoplastic polyester elastomer, TPEE), etc.
Most of the olefin-based TPE are block copolymer in which hard polypropylene, polystyrene, polyethylene, nylon, styrene-acrylonitrile and soft ethylene propylene diene rubber (EPDM), natural rubber, and styrene-butadiene rubber (SBR) are copolymerized. The block copolymer of the olefin-based TPE is mainly a random copolymer. Recently, a method has been suggested in which a metallocene catalyst is used or living polymerization is introduced to improve the physical property (see Korean Patent Publication No. 2012-0052385, and 2011-0114475, olefin-based diene copolymer).
As the styrene-based TPE, polystyrene polybutylene binary copolymer (SBS), polystyrene/poly(ethylene-propylene)/polystyrene tercopolymer (SEPS), polystyrene/poly(ethylene-butylene))/polystyrene tercopolymer (SEBS) are manufactured and merchandised by Clayton Polymers Ltd. under the registered trade name of “clayton”. Commercially available similar products include several such as solprene series and calprene series from Diansol Co., and products from Septone Co.
The styrene content of the above mentioned products is 10 to 40 wt % depending on required degree of strength and heat resistance. However, since the commercialized product contains polystyrene as a block copolymer form, there exists limitation in improvement of heat resistance due to glass transition temperature of polystyrene (100° C.) even in the case where the styrene content is increased.
Thus, there still remains difficulty in the application to a field which requires high heat resistance such as automobile components including CVJ boot and hose, or codes used in electronic components, and connectors of portable devices.